Is my CH/HW fully pumped? Is it two-pipe?

Discussion in 'General Plumbing Help' started by phloaw, Sep 30, 2019.

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  1. Sep 30, 2019 #1

    phloaw

    phloaw

    phloaw

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    Hi,
    I'm having problems understanding the exact configuration of the CH/HW piping in my house.
    In particular, I have to understand where and how to place piping for additional radiators at the upper floor.

    My configuration is the classical one: loft cistern, indirect cylinder on the upper floor, gas boiler on the ground floor. (my house is a two-floor terraced house, quite standard I'd say)
    This is the official installation diagram taken from the boiler's installation guide (I think "heat exchanger" can be identified with "boiler" for our purposes):

    https://i.postimg.cc/5y75Qytm/MEXICO-SLIMLINE2-CF40-CF50.png



    Contrasting that, this is how the boiler plumbing actually looks, from the left side (the smaller pipe on the bottom is irrelevant since it just passes through the boiler):


    https://i.postimg.cc/Df8RNxGB/IMG-20190921-170802.jpg


    and from the right-hand side:

    [​IMG]

    Given the number of pipes (4) attached to the boiler, and given the first figure, it looks like a non fully-pumped system.
    However, the location and number of valves: one for HW (top right last picture) and one for CH (bottom right of last picture) suggests a fully-pumped one.

    Any clue of what the actual situation is? Any test I could take myself to ascertain that?
    And what about the radiators configuration? Is there a way to know if it's a two-pipe or one-pipe system?
    As I mentioned, my main reason to know that is the perspective addition of radiators to the existing CH.

    Thanks!
     
  2. Oct 1, 2019 #2

    Diehard

    Diehard

    Diehard

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    Not sure what that Mexico Slimline diagram is showing.
    What is an "indirect cylinder"?

    The system appears to be an old gravity heating system with a pump added.

    What does CH represent?

    For heating only, a one-pipe system vs a two-pipe system would be a series vs parallel piping arrangement, respectively.
    For example, series is EXIT from one radiator is INLET to the next radiator.
    Parallel is one common line feeds into all radiators while the exits from all the radiators return in a separate common return line.

    What are the 4 pipes that enter or exit the boiler?

    What's the flow direction of that circulator pump?

    What are those boxes shown on the vertical pipe that have wire running to them?
     
  3. Oct 1, 2019 #3

    phloaw

    phloaw

    phloaw

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    The relevant part is the left-hand one, showing the schematic pipework: how the boiler should be piped.

    A hot water storage working by heat exchange:
    https://www.diyplumbing.co.uk/direct-indirect-hot-water-cylinders-whats-the-difference/

    Ok, that sounds interesting. Why did they add pump and valves? :)

    Central heating (as opposed to HW, hot water).

    I know all of that, but I'm having problem understanding which kind of CH I have.

    I don't know: I guess that would answer my question :)
    I'd need to uncover walls/floors to find out: maybe you can suggest a less disruptive option? :)

    I need to double-check, but I guess it pumps downwards.

    These are the electric valves to control HW (upper valve) and CH (lower valve): they are wired to the programmable controller (not shown here).
    This valve configuration is usually found in fully pumped systems (hence my bewilderment):[​IMG] :
     
  4. Oct 1, 2019 #4

    Diehard

    Diehard

    Diehard

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    Oh I see what you have now. I didn't realize the distinction between your HW and your CH was talking about the DOMESTIC HOT WATER (potable) vs your heating HW for your central heating system. Probably just that I'm not in the heating business, at all, but am familiar with the more modern, cistern free set-ups.

    So in your case they have a single circulating pump being used for both the CH as well as the domestic hot water system, with individual solenoid valves controlling when the CH system is allowed to receive heat. Which, of course, is when the HW system temperature setting has been satisfied. (The domestic HW takes priority, which is the common design.) So that's why you have TWO zone valves. Two circulating pumps, I believe, is the typical way it's done on this side of the pond.

    So back to one pipe or two. The above diagram you included, showing a 2 pipe system, I assume is a generic example and is not necessarily your arrangement.

    I count 3 pipes entering or exiting the boiler since you say the small one on the left goes right through. From what I can see, that leaves the one coming out on the right that goes to the pump, the one on the left top and the one on the left bottom. What am I missing?
    The way I see it, the boiler could have only 2 pipes connected and it still could be a 1 or a 2 pipe CH system.

    Hopefully someone familiar with the various systems would know what the 3rd and/or 4th pipe, connected to the boiler, could be for.

    That "official installation diagram taken from the boiler's installation guide" shows 4 pipes to the Heat Exchanger/Boiler but shows 2 independent loops. One for the heating of the Domestic HW and one for the CH system.

    I don't know how you would confirm whether it's using a 2 pipe system or not without seeing the piping.
    Wait a second...
    Wouldn't a 2 pipe systems have some type of thermostatic control valve at each radiator, which would control the flow through that one radiator. Can't use them in a series piping arrangement.:rolleyes:o_O
     
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  5. Oct 11, 2019 #5

    phloaw

    phloaw

    phloaw

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    Sorry, I missed notifications about your reply.
    Your last point would make a lot of sense, and indeed I seem to have TRVs in two of the radiators (it's an old system, all the other rads don't have one).
    So this is a strong indicator of a two-pipe system, although I understand that, theoretically, TRVs could be fitted even on a one-pipe system...
     
  6. Oct 11, 2019 #6

    Diehard

    Diehard

    Diehard

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